[DAS] Re: Our identifier doc and proposal

[Lincoln Stein]

Hi Brian, Erich,

I agree with Brian that when we're talking about the request from the
client to the server the class information isn't necessary.  When
there's information coming back from the server to the client, it's
useful for class information (Erich's OID_CLASS) to be attached to the
identifier.

Lincoln

Brian King writes:
 > 
 > 
 > > The pairing of OID and OID_CLASS represent discrete, fixed
 > > minimum requirements for preservation of information content. 
 > 
 > I don't see why this is true.  The class information is in the datasource,
 > not the client, so if you have a universally unique ID then the server
 > should know how to retrieve and construct a class instance.  The data
 > returned to the client should have enough information to determine the
 > class.  
 > 
 > I can see that it would be convenient for the client to know the object
 > class from the identifier prior to the query, but there are other ways to
 > get that information.  For example, if the ID is a reference within an XML
 > document, then you may know the class by the context, or at least know a
 > base class.  Or you could query the server to say "what is the class of the
 > object with ID 'ZZZZ'".  There have been cases in our systems we've changed
 > data by moving it into a new subclass. But querying by ID would still return
 > the same data.  Should the IDs now change to have the subclass name?  Should
 > I be able to query by encoding either class or superclass in the ID?  Do we
 > need to specify authority when we specify class to say whose ontology it is?
 > I don't think embedding this type of meta-data in the ID will be a stable
 > design.  
 > 
 > Regarding the I3C ID "paths", you're right that this is open to abuse.  I'd
 > rather call the path a "hierarchy".  It is not a physical path in a
 > filesystem or a path in a document; it is just a classification of the data
 > source.  This seems consistent with the URN RFC.
 > 
 > Brian

-- 
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Lincoln D. Stein                           Cold Spring Harbor Laboratory
lstein@cshl.org			                  Cold Spring Harbor, NY

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